Cellular and stromal edema are primary causes of decreased corneal transparency. This proposal is concerned with the physiology and biophysics of the corneal membranes in relation to their participation in the control of corneal hydration using the rabbit as an animal model. The mechanism of epithelial Cl transport will be studied in detail by determining the kinetics of the membrane "pump" and the role of the paracellular pathways. A mathematical model for corneal hydration dynamics will be extended to include pathways. A mathematical model for corneal hydration dynamics will be extended to include the effects of unstirred layers in cell cytoplasm and bathing media. With this extension the phenomenological permeability coefficients of the corneal membranes will be determined for a variety of solutes. The influences of sympathetic nerves in the cornea on trasport will be examined with combined electrophysiological and neuroanatomical mapping procedures to assess the role of these fibers in epithelial transport and growth.